An essential control circuit in any motor driven apparatus is the motor brake control circuit which is responsible for disconnecting or braking the motor in the event of a system malfunction.
A typical example of such a requirement is that of a document processing apparatus wherein a motor driven transport is used to move documents through an optical scanning or reading system in order to extract information from the documents. In the event of a malfunction, such as a document jam condition, it is essential that the motor be disconnected to stop the movement of documents through the system. Typically motor braking systems, which are employed to prevent equipment damage or operator injury as a result of a system malfunction, employ a combination of mechanical and electrical brakes which require precision adjustment and independent power excitation. A typical mechanical/electrical braking system significantly increases the complexity and cost of the motor driven system.
The invention disclosed herein avoids the necessity for the conventional mechanical/electrical brake system by utilizing a standard AC induction motor without detracting from its normal motor operation.